Conservative Supreme Court Justices expressed strong reservations today about a key provision of the Voting Rights Act that is intended to protect the rights of minorities and suggested it could be in danger.

That section of the landmark 1965 law says that certain states, mostly in the South, must get any changes to voting regulations precleared by federal officials in Washington, D.C.

Solicitor General Donald B. Verrilli Jr. began arguments at the Court Wednesday by saying that the Voting Rights Act "made a huge difference in transforming the culture of blatantly racist vote suppression that characterized parts of this country for a century. Section 5 preclearance was the principal engine of that progress."

But Chief Justice John Roberts expressed concern that Congress, when reauthorizing the law in 2006 for 25 more years, used an outdated "coverage formula" that singled out only a few states, mostly in the South. He asked Verrilli: "Is it the government's submission that the citizens in the South are more racist than citizens in the North?"

The jurisdictions covered under the law include Alabama, Alaska, Arizona, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia, as well as portions of California, Florida, Michigan, New Hampshire, New York, North Carolina and South Dakota.

Justice Samuel Alito said, "There's no question that the Voting Rights Act has done enormous good." But he said that when Congress reauthorized it, it should have considered a new determination of which states should be covered. "Maybe the whole country should be covered. Or maybe certain parts of the country should be covered based on a formula that is grounded in up-to-date statistics, " he said.

Justice Antonin Scalia spoke at length about the fact that the 2006 congressional vote to reauthorized the act was nearly unanimous.

"I think it is attributable, very likely attributable, to a phenomenon that is called perpetuation of racial entitlement. It's been written about. Whenever a society adopts racial entitlements, it is very difficult to get out of them through the normal political processes.

"And I am fairly confident it will be re-enacted in perpetuity unless a court can say it does not comport with the Constitution," he continued. "You have to show, when you are treating different states differently, that there's a good reason for it. "

Scalia said, "That's the concern that those of us who have some questions about this statute have. It's a concern that this is not the kind of a question you can leave to Congress."

After the dialogue, Roberts gave Verrilli an extra five minutes. "Thank you," Verrilli said, smiling. "I may need it for that question."

"We are talking about the enforcement power that the Constitution gives to the Congress to make these judgments to ensure protection of fundamental rights," said Verrilli.

He added that he thought it would be "extraordinary" to look behind the judgment of Congress on the basis of "that sort of motive analysis."

Scalia's question bothered Justice Sonia Sotomayor who later asked a lawyer for Shelby County, Ala., "Do you think Section 5 was voted for because it was a racial entitlement?" And she also said, "Do you think that racial discrimination in voting has ended and there is none anywhere? "

Sotomayor, one of the four liberals on the court, emerged as one of the most vocal defenders of the law.

Bert W. Rein, the attorney challenging Section 5, said that the South had changed and that the coverage formula should not have been reauthorized.

But Sotomayor cut him off. She said that even if some portions of the South had changed, "your county pretty much hasn't."

"Why would we vote in favor of a county whose record is the epitome of what caused the passage of this law to start with," she asked.

Justice Anthony Kennedy, who could be a crucial vote, asked a question that showed skepticism of Rein's position. He referred to Alabama's history of discrimination and noted that the state might be considered under any coverage formula.

"Why are you injured under this one?"

But as he had previously stated in a related case in 2009, Kennedy seemed concerned about the federalist implications of the law on the states. At one point he compared Alabama's sovereignty with the "trusteeship of the United States government."

Justice Elena Kagan defended the 15,000-page legislative record Congress developed after holding 21 hearings. "It's hard to see how Congress could have developed a better and more thorough legislative record than it did," she said.

Justice Clarence Thomas said nothing during arguments, but in 2009 he said he believed Section 5 " exceeded Congress' power to enforce the 15th Amendment."

In the audience were prominent civil rights activists, including the Rev. Jesse Jackson, the Rev. Al Sharpton, Rep. John Lewis, D-Ga., and Cecilia Marshall, the widow of former Supreme Court Justice Thurgood Marshall.

Protesters gathered on the steps outside the court before arguments began. They held signs with such messages as "Protect My Vote," and "My Vote, Our Rights, Our Fight."

Demonstrators from the Alliance for Justice lined up in front of the Supreme Court steps.

Jackson, Sharpton and Lewis spoke for the group, and were joined by Rep. Marcia Fudge, D-Ohio, House Minority Leader Nancy Pelosi, Rep. Judy Chu, D-Calif., and Ruben Hinojos, D-Texas, among others.

Fudge, chairwoman of the Congressional Black Caucus, had a clear retort to the arguments against Section 5: "You will not win. You will not win this battle."